Immune biomarkers alterations in post-traumatic stress disorder: A systematic review and meta-analysis

•The meta-analysis including 40 articles and 42 samples.•The meta-analysis provided evidence for elevation of pro-inflammatory cytokines and WBC in PTSD.•Sex, exposed to trauma, comorbid MDD, and psychotropic medications are the sources of heterogeneity. : Studies have reported the changes of immune biomakers in post-traumatic stress disorder (PTSD), but the results were conflicting. Our aim was to investigate the changes of immune biomarkers in PTSD. : Literatures investigating the changes of immune markers in PTSD published in English were systematically searched through PubMed, Embase and Web of Science. We conducted random effects meta-analyses relating PTSD to immune biomarker concentrations and using subgroup analyses to resolve heterogeneity. : A total of 2606 articles were screened and 42 samples were included by the systematic review. The levels of interleukin-1β (IL-1β, P = 0.01), IL-2 (P = 0.006), IL-6 (P = 0.0002), interferon-γ (IFN-γ, P = 0.004), tumor necrosis factor-α (TNF-α, P = 0.004), C-reactive protein (CRP, P = 0.0003) and white blood cell (WBC, P = 0.01) were higher in PTSD than healthy controls (HC). Subgroup meta-analyses for psychotropic medication showed the levels of IL-1β and IL-2 were not increased in the PTSD. Subgroup meta-analyses for whether HC exposed to trauma showed the levels of IL-1β and IL-6 were not increased in the PTSD. Egger´s test revealed there was no publication bias. However, there was significant heterogeneity across studies for immune markers other than for WBC (P = 0.14, I2 = 45%). Subgroup analyses based on sex, HC exposed to trauma, PTSD comorbid major depressive disorder, PTSD on psychotropic medications partially or completely resolved heterogeneity for some immune biomarkers. : This meta-analysis provides evidence for elevation of IFN-γ, TNF-α, CRP, and WBC in PTSD.